Recently, there have been an increasing awareness of and a higher interest in breast cancer. To provide early detection of breast cancer, for example, clinical diagnoses using mammography, ultrasound imaging, or the like (screening inspections) have been widely performed. When a breast cancer is detected, surgical resection is performed in principle. The resected tissue is subjected to pathological diagnosis (pathological inspection) under a microscope to make sure that, for example, the tissue of breast cancer has been completely excised. Furthermore, as an example technique used to inspect body tissue, a technique of Patent Literature 1 (Japanese Application Publication No. 2006-102360) is proposed. The technique according to the Patent Literature 1 relates to, for example, an apparatus of irradiating body tissue with infrared light, acquiring an image of subcutaneous vessels on the basis of the infrared light reflected by the body tissue, and displaying biometric information.
Because inspections and diagnoses of breast cancer require accuracy, it is desired that reliable information on a breast cancer area, such as breast cancer tissue, be acquired. However, human body tissues have optical properties such as light absorbance, transmittance, and reflectance that vary depending on the composition of the human body, and this difference may make it difficult to obtain reliable information on breast cancer areas.